Understanding the Safety Issue
Whenever the sun is shining, solar PV panels combine to generate lethal DC voltages that simply cannot be turned off.
The existing isolation system employed on most rooftop solar installations does nothing to stop the panels from combining and producing lethal DC voltages throughout the array.
The placement of a DC switch/isolator, as shown in figure 1 (whether placed on the roof, next to the inverter or both), will still allow the generation of lethal accumulated DC voltage throughout the panels and associated wiring, highlighted in red. As a consequence, these installations are a continual source of danger for maintenance and emergencies, including fire throughout the world.
When a Solar Safety ShutOFF is incorporated into your solar installation and turned off absolutely no combining of lethal DC Voltage occurs. The Solar Safety ShutOFF may be operated at the switchboard or as remote as the local substation. This feature is advantageous in a storm, flood, bushfire or even maintaining the electricity grid (stopping back feeding inverters)
When things go wrong with current isolation methods
To provide sufficient energy from solar panels to inverters with minimum losses increased voltages have been required for the generation of solar installations. For the Australian domestic market, a cap of 600VDC was introduced. Unfortunately, all forms of isolation have focussed on switching the combined output of the panels leaving the issue of lethal DC potential throughout the entire solar installation, even when all isolators are off. Because a solar array continues to combine panels and generate electricity whenever the sun is shining, all components are subject to continuous DC potential. If damaged, this solar generator may cause instant combustion at any point in the solar installation. More alarming is that in many cases the Fire Brigade have needed to implement extra precautions to extinguish roof fires where solar panels are installed – for fear they may receive a lethal electric shock – whether the panels were the cause of the fire or not.
Unprotected solar arrays accumulate and produce lethal levels of DC voltage increasing risk to homeowners, emergency service personnel and anyone accessing the roof area for general maintenance of the solar panels or roof area (cleaning gutters etc).
Damaged panels, wiring, inverters or dc isolators can cause fire due to the continuous power feed from solar panels.
UL Report Findings
Some findings provided by Underwriters Laboratories:
* Turning off an array is not as simple as opening a disconnect switch. Unlike a typical electrical or gas utility, on a PV array, there is no single point of disconnect.
* Tarps offer varying degrees of effectiveness to interrupt the generation of power from a PV array. Also, firefighting foam should not be relied upon to block light.
* PV systems are capable of producing electrical power sufficient to cause a lock-on hazard.
* Severely damaged PV arrays are capable of producing hazardous conditions ranging from perception to electrocution. Damage to the array may result in the creation of new and unexpected circuit paths.
* Damage to modules from tools may result in both electrical and fire hazards.
* Severing of conductors in both metal and plastic conduit results in electrical and fire hazards. Care must be exercised during ventilation and overhaul.
For more information please read UL Report findings: PV-FF_SafetyFinalReport.pdf
The Solution to rooftop solar panel fires
The Solar Safety ShutOFF may be added to any new or existing solar installation and provides true safety for any solar installation. The Solar Safety ShutOFF can be installed on homes, farm sheds, schools and commercial buildings and can be easily operated by home owners, emergency services personnel, tradespeople and roof maintenance personnel.
When the Solar Safety ShutOFF is fitted to your home, anyone may stop the generation of electricity of the solar panels simply by following the standard solar shutdown procedure located at the meter box. In an emergency, when access to the meter box is limited the entire solar array may be deactivated, removing all lethal DC voltages just by disconnecting the incoming power at the house, the street or the nearest substation. This then provides a SAFE environment for all emergency personnel, tradespeople and you to access the solar PV system and roof knowing that NO lethal DC voltages are being generated anywhere in your solar installation including the solar panels and associated wiring.
The Solar Safety ShutOFF is the first step in resolving the safety issues accompanied with solar installations by providing the only air gap solution to shutting down an entire solar installation just by disconnecting the incoming grid supply. Solar Safety ShutOFF provides the:
* Ability to switch off any solar generator both locally and remotely, providing a safe environment for anyone accessing a roof.
* Does not place operator at risk if solar array is damaged or the roof is electrified.
* Utilises the latest air gap isolation technologies providing up to 4mm air gap in less than 5 milliseconds.
* Provides true module level shut down isolation.
* When shut off, it leaves zero DC voltage circulating anywhere in system.
* Ability to clearly indicate safe solar panel isolation via existing inverter.
* Ability to switch off when a predetermined temperature has been reached (if heat is detected from an internal or external fire the entire system will safely shut down).
* Ability to shut down solar generation independent from the solar panels.
* Prevents solar panels back feeding into the electricity grid.
* Allows emergency services an immediate and unrestricted path to attack a fire or emergency situation rather than lose precious time performing risk assessments or not be willing to go on the roof due to increased risk of electric shock.
* Electricians would be able to work on the array and change faulty components knowing that NO lethal voltage can be generated.
* Anyone would have safe access to work on or just near the array without fear of finding themselves in a hazardous situation caused by an unknown fault or damage to the array.
* Prevents potential for electric shock when cleaning solar panels.
* Is compatible with Arc Detection Units which can provide 24/7 Safety monitoring and control.
* Can be installed on any new or existing system.
* Cost effective and safe.
For more information visit www.remotesolarisolator.com
